Hi
You may be needing the assistant to design strategy pertaining to marketing and sales. However, that is really not possible if you simply cannot have overall snapshot of organization of all of the 10 marketplaces.
I'm experienced in designing consolidated dashboard for multiple marketplace, so you can have the following information in a single excel file,
All Listings, in each marketplace, with variation in each listing. This includes currently help inventory, order to your vendors (which is about to be in your inventory), shipped to Amazon, Amazon having inventory, Sales of Last 30-90 days per SKU and ASIN, forecasted sales of next week, and therefore forecasting required inventory. This also include, ratings of each listing and how it is being improved day-by-day.
We can have detailed discussion if you like to further understand the concept.
Hope to hear from you
Cheers